Neonicotinoid Pesticides and Bees

Neonicotinoid Pesticides and Bees

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Timothy Lawrence , Director, WSU Island County Extension, Walter S. Sheppard , Professor and Chair, Department of Entomology, WSU
Neonicotinoids are a class of pesticide that has become popular recently because of their relative safety and effectiveness. However, "neonics" as they are nicknamed, may have a possible role in the rise of Colony Collapse Disorder, a phenomenon in which whole colonies of honey bees suddenly die or disappear. This paper discusses the possible relationship between the pesticide and the disorder and what precautions can be taken to minimize the risk to honey bees, native bees, and other pollinators.
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Recently, concern has been raised regarding the impact of a common class of pesticide known as neonicotinoids (pronounced neo-nih-CAH-tin-oids) on honey bees, (Apis mellifera, Figure 1) and native bee pollinators. Many people feel the decline in honey bee populations known as Colony Collapse Disorder (CCD) is directly linked to the increased use of these products.

In this paper, we will discuss the use of neonicotinoids as well as declines in honey bee populations. Finally, we will review what is currently known about the relationship between neonicotinoid pesticides and honey bees.

What are Neonicotinoids?

Neonicotinoids are systemic insecticides that are taken up by a plant through either its roots or leaves and move through the plant just like water and nutrients do. These insecticides provide very effective control of piercing and sucking insects. Over the last few years, the neonicoti­noid class of insecticides has become important for use in agriculture and home landscapes. There are currently more than 465 products containing neonicotinoids (often called “neonics”) approved for use in the state of Washington. Approximately 150 are approved for use in the home or garden.


Figure 1. Honey bee on apple blossom. Bees are an important component of Washington’s seven-billion-dollar apple industry. Much of the food we eat is dependent on honey bees for pollination. Photo courtesy of Nik Wiman, Oregon State University.
Neonicotinoids are relatively safe for use around people, animals, and the environment (Mohamed 2009; Tomizawa 2004). Because of their effectiveness and relative safety, neonicotinoids have become one of the fastest growing classes of pesticides used in agriculture as well as in home and garden products (Jeschke and Nauen, 2008).

One of the main advantages for using neonicotinoid prod­ucts is that they move systemically within the plant, thus reducing the direct pesticide exposure to both the appli­cator and the environment. Ironically, it is this systemic action that makes the neonicotinoids a problem for honey bees and other pollinators: because a neonicotinoid pesti­cide spreads within the entire plant, it can also be found in the nectar and pollen of the flowers.

Bee Exposure

In laboratory experiments, researchers have documented several neonicotinoid products that are toxic to bees. Depending on the amount of exposure to neonicotinoids, the effect on bees can be either sub-lethal or lethal. The sub-lethal effects of neonicotinoids include impaired learn­ing behavior, short- and long-term memory loss, reduced fecundity (fertility and reproduction), and altered foraging behavior and motor activity of the bees. Researchers have documented similar issues with other pesticides includ­ing some products used by beekeepers to control Varroa, a parasitic mite of the honey bee. Neonicotinoids have also been implicated, along with some fungicides, in either depressing bees’ immune systems or increasing their sus­ceptibility to biological infections (Wu et al., 2012; Pettis et al., 2013).

Exposure levels from dust created during planting of neonicotinoid-treated seed are known to have a devastat­ing lethal impact on honey bees. However, this mode of exposure can be avoided and more work needs to be done on controlling levels of dust during planting. A more press­ing concern is the chronic exposure of bees to neonicoti­noids in nectar and pollen, as well as in water expressed from plants via a process known as guttation, that is picked up by foraging bees and brought back to the hive.

As is evident from the articles cited in Table 1, a great deal of research is currently under way, in both Europe and the United States, looking very intently at the effects of neo­nicotinoids on honey bees. Researchers at the University of Minnesota, Washington State University, and Washington Department of Agriculture are specifically looking at the issue of neonicotinoids in urban areas.



Copyright 2016 Washington State University

Published November, 2013

Use pesticides with care. Apply them only to plants, animals, or sites as listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.

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